U.S. patent number 11,142,432 [Application Number 16/786,865] was granted by the patent office on 2021-10-12 for safety load hook.
This patent grant is currently assigned to pewag austria GmbH. The grantee listed for this patent is pewag austria GmbH. Invention is credited to Bernhard Oswald.
United States Patent |
11,142,432 |
Oswald |
October 12, 2021 |
Safety load hook
Abstract
A safety load hook with a lower part having a hook throat to
which a pivotable upper part is fastened, which, in an open
position, allows a load to be suspended on the hook throat and, in
a closed position, blocks the hook throat. The upper part is
blockable in the closed position by a locking arrangement which
includes a locking lever that is pivotable into a release position
and a locked position, is pre-tensionable into the locked position
by a tensioning spring, is fastened to the lower part with the
tensioning spring via the support bolt and, in the locked position,
engages in a receiver on the upper part by way of a shaped
projection. The locking lever includes a lever on its side opposite
the shaped projection, with a center of mass on the lateral surface
of the receiving bore for the support bolt.
Inventors: |
Oswald; Bernhard (Kapfenberg,
AT) |
Applicant: |
Name |
City |
State |
Country |
Type |
pewag austria GmbH |
Kapfenberg |
N/A |
AT |
|
|
Assignee: |
pewag austria GmbH (Kapfenberg,
AT)
|
Family
ID: |
1000005858922 |
Appl.
No.: |
16/786,865 |
Filed: |
February 10, 2020 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
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US 20200255265 A1 |
Aug 13, 2020 |
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Foreign Application Priority Data
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|
|
|
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Feb 12, 2019 [DE] |
|
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10 2019 103 517.1 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B66C
1/36 (20130101) |
Current International
Class: |
B66C
1/36 (20060101) |
Field of
Search: |
;294/82.17,82.2,82.22,82.33 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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2 489 760 |
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Jun 2005 |
|
CA |
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2 425 867 |
|
Dec 1974 |
|
DE |
|
10 2007 027 746 |
|
Dec 2008 |
|
DE |
|
0 080 955 |
|
Jun 1983 |
|
EP |
|
0 085 631 |
|
Aug 1983 |
|
EP |
|
2 491 901 |
|
Apr 1982 |
|
FR |
|
1 430 543 |
|
Mar 1976 |
|
GB |
|
H09-67079 |
|
Mar 1997 |
|
JP |
|
8500447 |
|
Aug 1986 |
|
SE |
|
Primary Examiner: Kramer; Dean J
Attorney, Agent or Firm: Christensen, Fonder, Dardi &
Herbert PLLC
Claims
The invention claimed is:
1. A safety load hook, comprising: a lower part, which defines a
hook throat; an upper part pivotably fastened to the lower part by
a connecting bolt, the upper part pivotable to an open position to
allow a load to be suspended in the hook throat of the lower part
and pivotable to a closed position that blocks the hook throat of
the lower part such that an introduction of the load to be received
into the hook throat or removal of a load held in the hook throat
is prevented, wherein in the closed position, the upper part is
blockable in relation to the lower part by a locking arrangement
which includes a locking lever with a receiving bore, the locking
lever being pivotable about a support bolt arranged in said
receiving bore into a release position and into a vertical locked
position, is pretensionable into the vertical locked position by a
tensioning spring, is fastened to the lower part via the support
bolt together with the tensioning spring and is engageable by way
of a shaped projection in an associated shaped receiver to the
upper part in the locked position, wherein the locking lever
includes, at a side opposite the shaped projection with reference
to the receiving bore, a lever portion, a center of mass of the
locking lever lying substantially on the lateral surface of the
receiving bore for the support bolt or inside the cross sectional
area surrounded by the lateral surface, and the lever portion
comprises a free end surface by way of which it is supported on an
associated support counter surface on the lower part in the locked
position.
2. The safety load hook as claimed in claim 1, where the center of
mass of the locking lever lies on the center axis of the receiving
bore for the support bolt.
3. The safety load hook as claimed in claim 1, where the lever
portion of the locking lever defines a recess in which the
tensioning spring is held in its assembly position.
4. The safety load hook as claimed in claim 3, where the recess of
the lever portion is delimited on both sides by a side flank of the
lever portion in each case for receiving the tensioning spring.
5. The safety load hook as claimed in claim 4, where the center of
mass of the locking lever lies centrally between both side
flanks.
6. The safety load hook as claimed in one of claim 1, where the
lever portion of the locking lever is supported on an associated
counter surface on the lower part in the locked position via a
substantially rectilinear or convexly curved end surface on the
free end.
Description
PRIORITY CLAIM
The present application claims priority to German Patent
Application No. 10 2019 103 517.1, filed on Feb. 12, 2019, which
said application is incorporated by reference in its entirety
herein.
FIELD OF THE INVENTION
The invention relates to a safety load hook having a lower part,
which realizes a hook throat and to which an upper part is fastened
so as to be pivotable by means of a connecting bolt, which bottom
part, which is pivotable in relation to the lower part, allows a
load to be suspended on the hook throat in an open position and, in
a closed position, blocks the hook throat of the lower part
outwardly such that the introduction of a load to be received in
the hook throat or the removal of a load held there from said hook
throat is prevented.
BACKGROUND OF THE INVENTION
Safety load hooks are load hooks which are designed such that in
the closed position of the load hook, the hook throat of the lower
part is blocked completely or almost completely (with a remaining
small opening gap of up to 3 mm according to EN 818-6) and is held
in said closed position by a locking arrangement. Unintentional
release of a received load or of another element received in the
hook is consequently prevented.
In this case, the locking system has first to be released for the
open position of the lower part in order to be able to rotate the
upper part and, as a result, to be able either to remove the
received load from the hook mouth or to suspend the load to be
received in the hook mouth.
The locking arrangement, in this case, can consist of a locking
lever, a spring which holds said locking lever in a locked position
and a support bolt, by way of which the locking lever and the
spring are connected to the hook lower part.
Such an arrangement has largely shown itself to be safe up to now.
However, it has certainly been shown in practice that under certain
circumstances said arrangement can ultimately fail, namely in the
following cases:
If, due to an incorrect application, and too much force acts on the
upper part, it is possible in the locked position for the bolt of
the locking lever to shear off on account of the lever action then
acting on it. The locking action is then cancelled and the desired
secure connection between the load hook and its load is no longer
guaranteed.
In addition, if the load hook knocks against an object dynamically
in almost a vertical direction, it is also possible for the locking
action to be cancelled and the upper part to be able to open. This
happens if, on account of the dynamics of the operation, the weight
of the locking lever results in such a large amount of inertia that
it overcomes the force of the pretensioning spring and the locking
lever opens, as a result of which, once again, the upper part is
subsequently released.
The safety load hook from DE 10 2007 027 746 A1 provides a hook
which is pivotable in its entirety and can be moved into a closed
position and an open position. In the closed position, the hook is
held in a positive locking manner via a blocking element which is
latchable into a latching recess and, in turn, is able to be
released via remote control, wherein the hook itself is
pretensioned toward its release position via a spring. In the case
of said load hook, it is not possible for the disadvantages stated
further above to arise on account of the overall arrangement chosen
but using remote control is expensive.
In the case of the load hook design according to CA 2 489 760 A1,
the load hook is also locked locally by remote control in its
closed carrying position by means of a locking member which is
mounted in the housing of the lifting device, wherein, when it is
not situated in its carrying position, it is pretensioned toward a
pivoted-open position by means of spring tension. Here too, it is
also possible for the locking to be cancelled if the load hook is
knocked against an object as in the case of incorrect use of the
load hook with too great a force on the upper part. The
installation of remote control unit for the locking system is
certainly quite costly.
SUMMARY OF THE INVENTION
Proceeding from here, the invention seeks to propose a load hook of
the type named in the introduction where the undesirable unlocking
of the locking lever named further above in the case of incorrect
application of an excessive force on the upper part of the safety
load hook or in the case of the safety load hook being knocked
downward dynamically against an object in an almost vertical
direction is avoided without using a remote-controlled locking
system.
This is achieved according to the invention by a safety load hook
of the type named in the introduction where, in the closed
position, the upper part is blockable in relation to the lower part
by means of a locking arrangement which includes a locking lever
with a receiving bore, which locking lever is pivotable about a
support bolt arranged in said bore into a release position and into
a locked position, is pre-tensionable into the locked position by
means of a tensioning spring, is fastened to the lower part via the
support bolt by way of the tensioning spring and engages by way of
a shaped projection in an associated shaped receiving means on the
upper part in the locked position, wherein the locking lever is
realized on its side opposite the shaped projection with reference
to the receiving bore with a lever portion in such a manner that
the center of mass of the locking lever lies substantially on the
lateral surface of the receiving bore for the support bolt or
inside the cross sectional surface surrounded by the same, and the
locking lever is supported on the lower part in the locked position
via the free end of its lever portion.
In an embodiment, in this case, the center of mass of the locking
lever lies on the center axis of the receiving bore for the support
bolt.
In the case of the safety load hook according to the invention, a
locking lever is now used which is realized with a lever portion on
its side opposite the shaped projection with reference to the
receiving bore in such a manner that the center of mass of the
locking lever comes to lie substantially on the lateral surface of
the receiving bore for the support bolt or inside the cross
sectional surface surrounded by the same, consequently directly or
almost in the pivot point of the locking lever. This prevents
unwanted release of the locking arrangement if the load hook knocks
against an object dynamically more or less in the vertical
direction, because, in this case, practically no opening torque or
only a very small opening torque acts on the locking lever as a
result of the inertia that becomes free in the case of a knock
without there being any risk, in this case, of the force of the
pre-tensioning spring being overcome in an unwanted manner.
At the same time, in addition, in the case of the safety load hook
according to the invention, on the side opposite the shaped
projection with reference to the receiving bore of the locking
lever, the lever portion provided there is also still realized such
that the locking lever is supported on the lower part via the free
end of the lever portion in its locked position and consequently,
if incorrect use occurs with excessive force on the tip of the
upper part of the load hook, unwanted shearing off of the support
bolt of the locking lever is prevented as a result of the locking
lever being supported against the lower part.
If, according to the claim, the center of mass of the locking lever
is able to lie not only inside the cross sectional area surrounded
by the lateral surface of the receiving bore for the support bolt
but also "substantially" on the lateral surface of the receiving
bore, this should then take account of the fact that a realization
with a center of mass precisely on the lateral surface is often not
achieved in an exact manner in practice on account of the tolerance
deviations in the form of the locking lever which mostly occur
inevitably during production of such locking levers, if only small,
so that, as a result, a slight deviation of the position of the
center of mass of the locking lever a little outside the cross
section surrounded by the lateral surface should also be
included.
A particularly preferred design of the invention also consists in
that the lever portion of the locking lever is provided with a
recess, inside which the tensioning spring is held securely in its
assembly position, which facilitates assembly in a considerable
manner and makes the often necessary use of an assembly aid for
mounting the tensioning spring in the assembly position
unnecessary.
It is additionally advantageous in the case of the invention when
the lever portion of the locking lever, in the locked position
thereof, is supported on the lower part on a correspondingly
associated counter surface via a substantially rectilinear or only
slightly convexly curved end portion on its free end, as a result
of which the locking lever is supported in a particularly effective
manner on the lower part compared to the case of a rounded or
punctiform support point.
The recess of the lever portion is preferably also delimited on
both sides of the lever portion by a side flank thereof in each
case for receiving the tensioning spring, as a result of which a
pocket-like recess for the tensioning spring which is simple to
produce is created.
In an embodiment, in the case of the safety load hook according to
the invention, the locking lever is also realized such that its
center of mass is present centrally between said two side flanks of
the lever portion.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in more detail below, in principle as an
example, by way of the drawings, in which:
FIG. 1 shows a center section of a safety load hook disclosed in
the prior art;
FIG. 2 shows a center section through a safety load hook according
to the invention;
FIG. 3 shows a non-sectioned side view of the load hook from FIG. 2
but in the open state;
FIG. 4 shows an enlarged sectional representation of the locking
arrangement inserted between the upper part and the lower part of a
safety load hook according to the invention, as can also be seen
from FIG. 2;
FIG. 5 shows a side view of the locking lever inserted in the
locking arrangement according to FIGS. 2 to 4 and
FIG. 6 shows a view of the locking lever in FIG. 5 looking in the
direction of the arrow A shown there.
DETAILED DESCRIPTION
FIG. 1 shows a center cross section of a safety load hook as
disclosed in the prior art, whilst the representations in FIGS. 2
to 6 show an exemplary embodiment of a load hook according to the
invention, the description of the disclosed load hook according to
FIG. 1 being helpful to understanding the exemplary embodiment of a
safety load hook according to the invention depicted in FIGS. 2 to
6.
In all the figures which are described below, identical parts are
always provided with the same reference symbols.
All the figures show a safety load hook 1 which comprises a lower
part 2 which provides a hook throat 3 for the suspending of a load
(which is not shown in all the figures) so that it can be conveyed
by way of the safety load hook 1.
Additionally provided is an upper part 4, which is fastened to the
lower part 2 so as to be pivotable via a connecting bolt 5 and is
provided, in turn, at the top with a suitable connection, such as,
for example, a coupling connection (as shown in FIGS. 1 to 3), or
an eyelet or a swirl.
The upper part 4 can be moved into a closed position by pivoting,
as shown in FIGS. 1 and 4: In said closed position, the hook throat
3 is completely blocked toward the outside (as shown in FIG. 2).
Instead of this, however, a small residual gap could still remain
in such a manner that in all cases a load suspended in the hook
throat 3 is always held securely by the load hook 1 whilst it is
being handled and is not able to pass unintentionally outward out
of the hook throat 3. Such a residual gap can be up to 3 mm
according to EN 818-6.
In order to be able to remove a load received in the load hook 1
from the hook throat 3 again or to be able to suspend a load in the
hook throat 3, the upper part 4 of the load hook 1 is pivoted open
outwardly about the connecting bolt 5 in relation to the lower part
2, as is shown in the side view in FIG. 3, which also applies in
the same way to the safety load hook 1 shown in FIG. 1.
As a result, an inlet opening, which creates the access for
inserting or removing a load, is created in the hook throat 3
between the lower part 2 and the upper part 4 of the load hook
1.
A locking arrangement, which is provided overall with the reference
symbol 6 and, as shown in FIGS. 1, 2, and 4, includes a pivotable
locking lever 7 which is pivotable about a support bolt 9 in
relation to the lower part 2 and comprises a receiving bore 8 (cf.
FIG. 5), through which the support bolt 9 extends and serves as a
pivot axis for the locking lever 7, is arranged between the lower
part 2 and the upper part 4 of the load hook 1.
The locking arrangement 6 additionally includes a tensioning spring
10, which, in the locked position of the locking arrangement 6, in
which the lower part 2 and the upper part 4 are locked relative to
one another with the load hook 1 in the locked position,
pretensions the locking lever 7 toward a locked position in which a
shaped projection 11, mounted on the locking lever 7, engages in an
associated shaped receiving means or receiver 12 on the side of the
upper part 4 that faces it, for realizing a latching device.
In the case of the known realization of the locking arrangement 6
shown in FIG. 1, the shaped projection 11 is realized in the form
of a small, outwardly projecting lever arm which, on its protruding
end, realizes in cross section a V-shaped end surface, by way of
which it engages in a shaped receiving means 12 in the form of an
indentation, which is realized correspondingly on the facing side
of the upper part 4, as a result of which the desired locking is
achieved.
The locking lever 7 is pretensioned, in this case, toward its
locked position by the pretensioning spring 10 so that when the
locked position is reached, as shown in FIG. 1, unwanted releasing
of the locking action is avoided.
When, in the case of the known arrangement according to FIG. 1, an
excessive opening force then acts on the upper part 4 of the load
hook 1 as a result of any incorrect application and the locking
arrangement 6 is situated in its locked position, it has certainly
been shown in practice that it is definitely possible for the
support bolt 9 to shear off on account of the lever action which is
exerted via the shaped projection 11 on the locking lever 7 and via
said locking lever on the support bolt 9, which results in total
failure of the locking action of the locking arrangement 6.
In addition, the arrangement from FIG. 1 can also result in the
load hook 1, if it knocks relatively dynamically against a stop in
the vertical direction, experiencing an opening torque which acts
on said locking lever in the opening direction, is directed in the
opposite direction to the pretensioning action of the tensioning
spring 10 and exceeds the pretensioning torque thereof as a result
of the energy of inertia of the locking lever 7, as a result of
which the shaped projection 11 is rotated out of the shaped
receiving means 12 and, consequently, once again, the locking
action between the upper part 4 and the lower part 2 is cancelled
in an unwanted manner.
In the case of the embodiment of a safety load hook 1 according to
the invention shown in FIGS. 2 to 6, the locking arrangement 6 used
there is used in a design that has clearly been modified in
relation to that from FIG. 1:
Reference is made first of all to FIGS. 4 to 6 to illustrate the
difference in more detail.
These show that here the locking lever 7, on its side located
opposite the shaped projection 11 with reference to the receiving
bore 8 for the support bolt 9, is provided with a lever portion 13
which realizes a counterweight within the frame of the design of
the locking lever 7 in relation to the shaped projection 11 with
reference to the receiving bore 8 and in this case is designed such
that the mass center point S of the locking lever 7 lies on the
lateral surface M of the receiving bore 8, as shown in FIG. 5, or
also inside the cross sectional area Q of the receiving bore 8
surrounded by the lateral surface M. In this case, the locking
lever 7 should be designed in a quite preferred manner such that,
in this case, the mass center point S still lies centrally in the
view of the locking lever 7 seen in viewing direction A from FIG.
5, as shown in FIG. 6.
However, during production of such a locking lever 7, it is not
always possible to guarantee that the center of mass S, if the
position thereof should lie on the lateral surface M of the
receiving bore 8, achieves such a position in a precise and exact
manner, since, as a result of inevitable manufacturing tolerances
in the case of the design thereof, slight deviations can in fact
occur thereto in this case, as a result of which the center of mass
S also perhaps comes to lie slightly a little outside the lateral
surface M, and the formulation that the center of mass S should lie
"substantially on the lateral surface M" takes account of this.
Realizing the locking lever 7 such that the center of mass S
thereof is to lie substantially on the lateral surface M of the
receiving bore 8 or inside the cross sectional area Q of the
receiving bore 8 surrounded by said lateral surface M, creates a
state which even in the event of the load hook 1 impacting strongly
in a vertical manner on a collision element, creates a situation in
which the mass moment of inertia of the locking lever 7 then acting
suddenly on the center of gravity S is so small that its action in
the opening direction of the locking lever 7 is no longer able to
overcome the pretensioning action of the same provided by the
tensioning spring 10 in the locking direction. This applies quite
particularly when (not shown in the figures) the locking lever 7 is
designed such that its center of mass S lies on the center axis of
the receiving bore 8 or also inside the opening region of the
receiving bore 8 surrounded by the lateral surface M.
As can be seen, in particular, from FIG. 3, in the case of the load
hook 1 shown, the design of the locking lever 7 and of the end
surface of the lower part 2 of the load hook 1 located opposite
said locking lever is realized such that the locking lever 7 holds
the upper part 4 in the open position thereof even in said open
position, by the shaped projection 11 coming to abut here by way of
its side flank 14, which is remote from the outside of the safety
load hook 1, against an outer contact surface 15 on the outside of
the upper part 4 and being held in said abutment contact by the
tensioning spring 10, as a result of which the upper part 4 is
prevented from pivoting back into the closed position thereof in an
unwanted manner. For the corresponding designs of the shaped
projection 11 and of the upper part 4, reference is made explicitly
to the designs of said parts shown in FIGS. 2 and 3.
The lever portion 13 of the locking lever 7, which is provided on
the side of the locking lever 7 located opposite the receiving bore
8 and the support bolt 9, is realized in its design such that it
comprises either a free end surface 16 which extends rectilinearly
(as shown in the figures) or a weakly curved end surface (not shown
in the figures), by way of which it is supported on an associated
support counter surface 17 on the lower part 2, as shown in FIGS. 2
to 4.
As said lever portion 13 of the locking lever 7 is located opposite
the shaped projection 11 of the locking lever 7 with reference to
the rotational axis created by the support bolt 9, even in the case
of an extremely strong torque which should act inadvertently on the
upper part 4 in the opening direction, rigid support on the lower
part 2 is achieved, as seen particularly well in FIG. 4, as a
result of the design of the locking lever 7 with the lever portion
13, as a result of which the support bolt 9 is no longer able to
shear off and also a large tilt moment of the upper part 4 in
relation to the lower part 2 is successfully supported.
In the case of said load hook in FIGS. 2 to 4, the tensioning
spring 10 sits inside a recess 19 in the lever portion 13, which is
delimited on both sides in each case by a side flank 20 and
realizes a type of receiving pocket in which the tensioning spring
is held in its assembly position.
To extend the shaped projection 11 in opposite directions, another
lever arm 18 is mounted on the locking lever 7, by means of which
it is possible to open the locking arrangement 6 from its locked
position and, as a result, to release the upper part 4 so that said
upper part, as shown in FIG. 3, is able to be rotated into its open
position in order to suspend a load in the hook throat 3 of the
lower part 2 or to remove a load which is suspended there. In the
open state, when the lever arm 18 is released, the tensioning
spring 10 presses the shaped projection 11 again by way of its side
surface 14 in the direction of the facing side of the upper part 4
until the side surface 14 abuts there against the outer contact
surface 15, as a result of which the position shown in FIG. 3
occurs in which the upper part 4 is held in its open position. Said
holding position of the upper part 4 can then, as soon as desired,
either be cancelled again by actuation of the lever arm 18 or by a
somewhat greater closing force which acts on the upper part 4, and
the latter can be transferred again into its closed position shown
in FIG. 2 in which the locking lever 7 can then also assume its
locked position, as shown in FIGS. 2 and 4, under the effect of the
tensioning spring 10.
* * * * *